The invention relates to a device comprising a sensor device with a detection device for determining information of at least a part of a surface of the sensor device, a display device comprising an electro-optical medium between two substrates, and a driver for driving the display device in dependence upon the information obtained via the detection. device.
The invention also relates to a sensor device for use in such devices.
Devices of this type (also referred to as touch panels) are generally known; in which different sensor mechanisms can be used. For determining information, it is possible to activate a part of the surface by scanning and measuring, for example activating via light (by means of, for example, a light pen) and by subsequently measuring induced currents or capacitively measuring electric voltages induced by pressure variation. The displayed information may vary from the co-ordinates of the part of the surface to the luminescence of the relevant part or possibly a menu activated thereby in computer applications.
A device of this type is described in U.S. Pat. No. 5,194,862. For the sensor device (realized on a panel) described in this patent, it is indicated how it can be used as an overlay for a liquid crystal display device (LCD).
When this type of device is used, notably in portable applications (mini-notebook computers, personal digital assistance devices, telecommunication), it is desirable that a minimal quantity of energy is used. Use is therefore preferably made of reflective display devices (LCDs) which make use of a reflector or reflective electrodes. To give such display devices a satisfactory reflecting power, they are provided with a light-scattering film on the surface where a polarizer is usually situated. The total stack of the light-scattering layer, the polarizer and often a retardation film is usually provided as a whole on the surface of one of the substrates. The manufacture of this stack on large surfaces with constant thicknesses of the sub-layers is very difficult from a manufacturing-technical point of view. Moreover, the fixation of the complete stack on the substrate involves many problems.
The sensor device comprises a substrate which is provided with a light-scattering film or a polarizer on its side facing the electro-optical medium.
The fixation of (a part of) the stack on the substrate of the sensor device (light-scattering film on glass) is technologically simpler than the fixation of the complete stack on the usually much thinner substrate of the display device (polarizer on glass or retardation film).
A polarizer may be advantageously provided on the substrate, together with the light-scattering film.
A preferred embodiment of a device according to the invention is characterized in that said substrate of the sensor device is further provided with an anti-reflex coating.
A further embodiment is characterized in that a substrate of the display device remote from the sensor device is provided with a reflector.
The reflector may be arranged on the inner side or the outer side of the substrate of the display device. The reflector is preferably arranged on the side, facing the electro-optical medium, of the substrate of the display device remote from the sensor device.
In a further embodiment, the substrate of the display device remote from the sensor device comprises a silicon substrate in which, for example drive switches are realized (active drive) or which incorporates further drive functions.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.